1. Field of the Invention
The present invention relates to a medical instrument.
2. Description of the Related Art
A prior art example of a medical instrument (see Patent Publication No. 2000-279418) for continuously endoscopically picking an organic tissue will now be described with reference to FIGS. 17A to 17D and 18A to 18E.
As shown in FIG. 17A, this conventional medical instrument 201 comprises an insert section 202 that can be inserted into an endoscope and an instrument control section 203 that is fixed to a proximal end portion of the insert section 202. The insert section 202 is composed of a sheath 204 and a tissue picking portion 205 that is fixed to a distal end of the sheath 204.
As shown in FIG. 18A, an inner tube 208 for use as a lumen for excised slice recovery is passed through the bore of the sheath 204. Further, forceps control wires 209a and 209b for operating a pair of forceps 212a and 212b (see FIGS. 17B and 17C), along with the inner tube 208, are passed through the bore of the sheath 204. The respective proximal ends of the control wires 209a and 209b are fixed integrally to a forceps control slider 234 (see FIG. 17A).
As is evident from FIGS. 17B and 17C, the forceps 212a and 212b have movable jaws 220a and 220b on their respective distal end portions. The movable jaws 220a and 220b grasp and excise a part of the organic tissue. Further, the forceps 212a and 212b have rocking arms 221a and 221b for rocking the movable jaws 220a and 220b on their respective proximal end portions. The approximate central portions of the forceps 212a and 212b are mounted on supporting pins 222a and 222b (see FIG. 18B), respectively. The forceps supporting pins 222a and 222b are attached to a tip cover 211, extend through flat portions 215a and 215b, respectively, of the tip cover 211, and can rock independently of each other.
The respective proximal ends of the rocking arms 221a and 221b are rockably fitted with forceps control wire holding pins 223a and 223b for use as rocking pins that hold the forceps control wires 209a and 209b, individually. These forceps control wire holding pins 223a and 223b penetrate through holes 229a and 229b formed in the rocking arms 221a and 221b, respectively.
As is also shown in FIGS. 18A to 18C, a suction nozzle 213 is formed integrally on the distal end of the inner tube 208. The suction nozzle 213 has an oval cross section that is perpendicular to the longitudinal direction of the insert section 202. Further, the distal end portion of the suction nozzle 213 that has a suction port 219 on its distal end projects into a tissue receiving space 227 of the movable jaws 220a and 220b through an opening portion 216 of the tip cover 211.
As shown in FIG. 17A, the instrument control section 203 has a suction port 238 connected to the proximal end of the inner tube 208 and a liquid conveying port 240 connected to the proximal end of a residual space 228. The suction port 238 is to be connected to a negative-pressure generator 235 by means of a tissue recovery container 237 and a suction tube 236. Further, a syringe 239 for use as fluid supply means can be connected to the liquid conveying port 240.
As shown in FIG. 17D, the tissue recovery container 237 is composed of a container housing that has six vials 246a to 246f and six vial inlet holes 249a to 249f provided corresponding to the six vials 246a to 246f, individually. The vials 246a to 246f serve as independent tissue traps that are independent of one another. In this case, the vials 246a to 246f are removably attached to their corresponding vial inlet holes 249a to 249f without failing to maintain airtightness.
The following is a description of treatment for the organic tissue by means of the medical instrument 201 constructed in this manner.
First, the interior of the body cavity is observed through the endoscope as the endoscope and the medical instrument 201 are moved in the body cavity, and the tissue picking portion 205 is guided to a position where it faces a subject tissue of a mucous membrane. Subsequently, the forceps control slider 234 is moved to the distal end side to push out the pair of forceps control wires 209a and 209b to the distal end side. Thereupon, the forceps control wire holding pins 223a and 223b rotate as they move together with the rocking arms 221a and 221b to the distal end side. Accordingly, the forceps 212a and 212b rock around the forceps supporting pins 222a and 222b, respectively, whereupon the movable jaws 220a and 220b swing open around the central axis of the tissue picking portion 205 (see FIGS. 17B and 17C).
When the movable jaws 220a and 220b are open, as shown in FIG. 19, thereafter, edge portions 225a and 225b of the movable jaws 220a and 220b are caused to engage a subject tissue 262. In this state, the forceps control slider 234 is moved to the proximal end side, so that the pair of forceps control wires 209a and 209b are pulled back to the proximal end side. Thereupon, the movable jaws 220a and 220b are closed to excise the subject tissue 262, and a tissue slice 263 is held in the tissue receiving space 227 of the jaws 220a and 220b (see FIG. 20).
When the tissue slice 263 is held and recovered in the tissue receiving space 227 of the jaws 220a and 220b in this manner, the negative-pressure generator 235 is actuated to evacuate air from the inner tube 208 and thus the suction nozzle 213, thereby forming a negative pressure therein. If a fluid is then fed into the residual space 228 in the sheath 204 by means of the syringe 239, the fluid is jetted out into the tissue receiving space 227 of the jaws through the opening portion 216 of the tip cover 211, and runs the tissue slice 263 into the suction nozzle 213. The tissue slice 263 that has been run in the suction nozzle 213, along with the supplied fluid, is sucked into the inner tube 208 under the negative pressure produced by means of the negative-pressure generator 235, and is carried into a suction line 255 of the tissue recovery container 237 through the suction port 238 without jamming. The tissue slice 263 that is carried into the suction line 255 is captured by a mesh filter 252a of the vial 246a. Further, the fluid that is sucked in together with the tissue slice 263a to the suction line 255 passes through the mesh filter 252a and a vial through hole 251a, and is sucked into the negative-pressure generator 235.
In the conventional medical instrument 201 constructed in this manner, the forceps control wires 209a and 209b are fixed by spreading, laser welding, etc. after they are passed through forceps control wire holding grooves 224a and 224b formed in the forceps control wire holding pins 223a and 223b. Since the forceps control wire holding pins 223a and 223b are spaced individually outward from the central axis plane of the forceps (or the plane of contact between the edge portions 225a and 225b of the movable jaws) (that is, the forceps control wire holding pins 223a and 223b are located at a good distance from a plane that passes through the longitudinal central axis of the tissue picking portion 205 (tip cover 211) and extends parallel to the longitudinal central axis of the forceps control wire holding pins 223a and 223b), outward end faces 223f of the forceps control wire holding pins 223a and 223b are obliquely formed to match a circumferential surface C of the forceps (see FIG. 18C). This is done because the outer diameter of the medical instrument must be made smaller than the inner diameter of a forceps channel of the endoscope, since the instrument is inserted in the forceps channel when it is used. In fixing the forceps control wires 209a and 209b to the forceps control wire holding grooves 224a and 224b in the forceps control wire holding pins 223a and 223b by spreading or laser welding, however, a satisfactory connection space (working space) for the forceps control wires 209a and 209b cannot be secured with use of the inclined working plane. Thus, positioning and fixing operations are harder than when a substantially horizontal plane is used. Naturally, in order to give priority to workability, the respective outward end faces 223f of the forceps control wire holding pins 223a and 223b may possibly be formed to be substantially horizontal surfaces in the state of FIG. 18C where the forceps control wire holding pins 223a and 223b are spaced outward from the central axis plane of the forceps. In this case, however, the corner portions of the substantially horizontal surfaces project from the circumferential surface, so that the maximum outer diameter increases. Thus, the resistance of insertion into the endoscope is so high that the operating efficiency lowers.
In the conventional medical instrument 201 constructed in this manner, moreover, the forceps supporting pins 222a and 222b are attached to the tip cover 211 and extend through the flat portions 215a and 215b, respectively, of the tip cover 211. Therefore, head portions 300 of the forceps supporting pins 222a and 222b are bound to project into the bore of the tip cover 211, so that the size of the suction nozzle 213 that is passed through the bore is restricted inevitably.
In the conventional medical instrument 201 constructed in this manner, furthermore, a part 264 of the tissue slice 263, excised and recovered, is inevitably nipped between the edge portions 225a and 225b of the movable jaws 220a and 220b when the subject tissue 262 is grasped and excised by means of the movable jaws 220a and 220b (see FIG. 20). This is because cutting edges on the edge portions 225a and 225b of the movable jaws 220a and 220b cannot completely excise the tissue. More specifically, the tissue picking portion 205 is separated from the subject tissue 262 without releasing the tissue, whereby the tissue is finally torn away. When the part 264 of the tissue slice 263 is thus nipped between the edge portions 225a and 225b of the movable jaws 220a and 220b, it is hard to move the tissue slice 263 into the suction port 219 if a negative pressure is applied to the suction port 219 to reflux the fluid to the suction port 219 through the opening portion 216 of the tip cover 211.
Naturally, in this case, the nipped tissue 264 can be released if the forceps control slider 234 is moved to the distal end side to open the movable jaws 220a and 220b. If the movable jaws 220a and 220b are fully opened, however, the tissue slice 263 inevitably adheres to the movable jaw 220a or 220b and leaves the suction port 219. In consequence, it is hard to suck in and recover the tissue. If the fluid is jetted out through the opening portion 216 of tip cover 211 in this state, the tissue slice 263 may possibly fall off the tissue picking portion 205 under the jet pressure of the fluid.
In order to move the tissue slice 263 successfully to the suction port 219 while releasing the nipped tissue 264, therefore, the movable jaws 220a and 220b should be opened slightly or by half at the most. However, the operator requires skill and subtle manipulation to operate the forceps control slider 234, thereby moderately opening the movable jaws 220a and 220b. Thus, the treatment inevitably takes extra time.